the area of a parallelogram with adjacent sides a and b and including $\displaystyle angle \theta $ is given by $\displaystyle A=absin\theta $. find the rate of change of A with respect to a when a=10, b=20 and $\displaystyle \theta=\frac{\pi}{6} $

pls guys take a look at the problem above, it appears it lacks sufficient information because the values for the rate of change were not given. prove me right if i am wrong, thanks